Cyclopropyl-bearing liquid crystal compounds and mixtures

ABSTRACT

The present invention is directed to compounds of the following General Formula I. The cyclopropyl-bearing liquid crystal compounds of Formula I of the present invention have a positive or negative dielectric anisotropy (Δ∈), an appropriate optical anisotropy (Δn), an appropriate clearing point (CP), good low-temperature miscibility with other liquid crystals, a low rotary viscosity, and good UV stability and high-temperature thermal stability, and therefore have good use value. The compounds of the present invention can be used for preparing positive and negative liquid crystal compositions and can also be employed in passive and active matrix displays.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Chinese Application No.201410764634.4, entitled “Cyclopropyl-Bearing Liquid Crystal Compoundsand Mixtures” and filed Dec. 12, 2014, the contents of which applicationare incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of liquid crystal compoundsand use thereof, and is specifically directed to cyclopropyl-bearingliquid crystal compounds and mixtures.

BACKGROUND OF THE INVENTION

Although Austrian scientist F. Reinitzer successfully synthesized theliquid crystal for the first time in 1888, there was no real developmentof the liquid crystal industry until about 30 year ago. Due to the manyobvious advantages of liquid crystal display materials, such as lowdriving voltage, micro power consumption, high reliability, being ableto display large amounts of information, color display, flicker-free andbeing able to realize flat-panel display, the liquid crystal monomersand liquid crystal display have undergone great development. So far, theliquid crystal monomers can be synthesized into over 10,000 liquidcrystal materials, of which, more than 1,000 liquid crystal materialsare commonly and frequently used, and can be classified into differentcategories by the characteristics of the central bridge bond and ring ofthe liquid crystal molecule, which mainly include biphenyl liquidcrystals, phenylcyclohexane liquid crystals, ester liquid crystals,alkynyl liquid crystal, liquid crystals with difluoromethoxy bridge,ethane liquid crystals and heterocyclic liquid crystals, etc. And liquidcrystal display has developed from the small TN or STN black and whitescreen to the big TN-TFT, VA-TFT, IPS-TFT or PDLC color screen.

Major novel liquid crystal display modes include optical compensatedbend (OCB), in-plane switching (IPS), vertical alignment (VA), the axisof symmetry microstructure LCD (ASM), twisted multi-domain liquidcrystal display and the like.

The liquid crystal cell of different display mode differs in design,driving method, liquid crystal molecule director and direction of glasssubstrate; and the liquid crystal molecule director and the direction ofglass substrate of the OCB mode and IPS mode are parallel, while theliquid crystal molecule director and the direction of glass substrate ofthe VA mode and the ASM mode is perpendicular when there is no appliedelectric field.

For IPS in parallel arrangement, the dielectric anisotropy (Δ∈) of theliquid crystal can be positive or negative.

In VA mode, all molecules of liquid crystal are perpendicular with thedirection of glass substrate and parallel with the vertical incidentright, when there is no applied electric field. And a good dark statewill be displayed when the polaroids are orthogonal, which enables suchdevice to have good contrast ratio, and in this case the dielectricanisotropy (Δ∈) of the liquid crystal must be negative. The opticalanisotropy (Δn), the thickness of the liquid crystal cell (d) and thewave length of incident right (λ) of the liquid crystal hardly influencethe contrast ratio. Besides, the response time of the VA mode is muchshorter than the twisted devices, about half of that of the latter.Under the influence of applied voltage, VA devices will mainly producethe bend deformation of liquid crystal molecules, and ECB devices willproduce the splay deformation of liquid crystal molecules and thetwisted display devices will produce the twist deformation of the liquidcrystal molecules, and their response time will be respectively inreverse proportion to the bend, splay and twist elastic constant. Andfor most liquid crystals, its bend elastic constant is usually largerthan its splay elastic constant, and its splay elastic constant islarger than the twist elastic constant, that is the reason why theresponse time of VA devices is relatively faster.

In order to further idealize the performance of the display devices,researchers are always devoted to study new liquid crystal compounds,and this contributes to the constant development of the liquid crystalcompounds and display devices.

Despite the application of cyclopropyl structure in liquid crystalcompounds was reported, the considerable performance deficiencies in thethen-reported compounds such as poor structure stability, largeviscosity and difficult to synthesize have prevent them from practicalapplication.

SUMMARY OF THE INVENTION

Surprisingly, the cyclopropyl-bearing liquid crystal compounds withstructural characteristics of Formula I have a positive or negativedielectric anisotropy (Δ∈), an appropriate optical anisotropy (Δn), arelatively high clearing point (CP), outstanding low-temperaturemiscibility with other liquid crystals, a low rotary viscosity (γ₁), andgood UV stability and high-temperature thermal stability, and can beapplied for the preparation of liquid crystal compounds of all types,and therefore have extensive and good application value.

Disclosed in the present invention is the liquid crystal compound ofFormula I:

wherein, R represents a hydrogen atom (H) or a C1-C5 alkyl;m, e, n each can be 0, 1 or 2;Z represents a single bond, —CF₂O—, —CH₂CH₂—, —CH₂O—, —C≡C—, —OCH₂— or—OCF₂—X represents F, CI, OCF₃, CF₃, CN, H, a C1-C5 alkyl, a C1-C5 alkoxy, aC2-C5 alkenoxy, a C2-C5 alkenyl or a C2-C5 fluoro-substitutedalkenyloxy;

each independently represents the phenylene, fluoro-substitutedphenylene, cyclohexylidene and one or more of the groups generated fromthe substitution of one or two unconnected CH2 in the cyclohexylidene byoxygen (O).

As a preferred embodiment, when n=1 or 2, the said

=phenylene or fluoro-substituted phenylene; when n=0, the said

=cyclohexylidene or the group or groups generated from the substitutionof one or two unconnected CH₂ in the cyclohexylidene by oxygen (O).

The pure compounds of Formula I are colorless, and will have differentproperties when the values of R,

Z, X, m and n differ. The said compounds can be applied for preparingpositive or negative liquid crystal mixtures and for multi-mode displaydevices, for example, OCB, TN, STN, positive or negative IPS, positiveor negative FFS, PVA, MVA, PSVA and UN²A, and therefore have a widescope of application.

In addition, the said compounds can be used as base materials for liquidcrystal mixtures, and may also be employed as additional materials to beadded into the liquid crystal base materials composed of compounds ofother types, for such purposes as to improve the dielectric anisotropy(Δ∈) and/or rotary viscosity (γ1) and/or threshold voltage (V_(th))and/or low-temperature contrast ratio and/or optical anisotropy (Δn)and/or clearing point (Cp).

The liquid crystal compounds of Formula I can be compounds containingdifluoro-methylenedioxy, for example, compounds of Formulas (I 1-I 9):

wherein, the definitions of R, n, X are same as defined in Formula I,and n is preferably 1 or 2, and (F) independently represents F or H.

Compounds with difluoro-methylenedioxy linking group in Formulas (I 1-I6) have in particular a large dielectric anisotropy (Δn), a large orappropriate optical anisotropy (Δn), good low-temperature miscibilitywith other liquid crystals, a low rotary viscosity, and good UVstability and high-temperature thermal stability.

Compounds with difluoro-methylenedioxy linking group in Formulas (I 1-I6) have different values of R,

Z, m and n, and when all variables have big or small polarizationtowards the molecule long axis direction, the value of dielectricanisotropy (Δ∈) can be between 5-50, X is preferably F, −(F) ispreferably —F, and the value of dielectric anisotropy (Δ∈) of thepreferred structure is between 20-40, and the preferred structure willalso have a low rotary viscosity (γ1); due to the different conjugationextent of liquid crystal molecules of different structures, the opticalanisotropy (Δn) can be between 0.05-0.40; and when m+n=2, the clearingpoint will be relatively low, however, when m+n>2, the clearing pointcan be as high as 100° C. or even over 150° C. In addition to suchcharacteristics, compounds with difluoro-methylenedioxy linking group inFormulas (I 1-I 6) also have good low-temperature miscibility with otherliquid crystals and are therefore able to improve the low temperaturecharacteristics of the mixed liquid crystal.

Liquid crystal compounds of Formula I, for example, compounds ofFormulas (II 1-II 13):

wherein, the definitions of R, n, X are same as defined in Formula I,and n is preferably 1 or 2, and (F) independently represents F or H.

Compounds of Formulas (II 1-II 13) have a large dielectric anisotropy(Δ∈), a wide range of optical anisotropy (Δn), good low-temperaturemiscibility with other liquid crystals, a low rotary viscosity (γ1), arelatively high clearing point (CP) and good UV stability andhigh-temperature thermal stability.

Compounds of Formulas (II 1-II 13) have different values of R,

Z, m and n, and when all variables have big or small polarizationtowards the molecule long axis direction, the value of dielectricanisotropy (Δ∈) can be between 0-30, X is preferably F, −(F) ispreferably —F, and the value of dielectric anisotropy (Δ∈) of thepreferred structure is between 5-25; due to the different conjugationextent of liquid crystal molecules of different structures, the opticalanisotropy (Δn) can be between 0.05-0.40; and when m+n=2, the clearingpoint can be between 20-150° C., however, when m+n>2, the clearing pointcan be as high as 150° C. or even over 250° C. In addition to suchcharacteristics, compounds of Formulas (II 1-II 13) also have goodlow-temperature miscibility with other liquid crystals and are thereforeable to improve the low temperature characteristics of the mixed liquidcrystal.

Liquid crystal compounds of Formula I, for example, compounds ofFormulas (III1-III12):

wherein, the definitions of R, n, X are same as defined in Formula I,and n is preferably 1 or 2, and (F) independently represents F or H, X₁represents a C1-C5 alkyl, C1-C5 alkoxy, C2-C5 alkenoxy or C2-C5 alkenyl,and X₁ is preferably a C1-C5 alkyl or C1-C5 alkoxy.

Compounds of Formulas (III1-III5) have a large negative dielectricanisotropy (Δ∈), a wide range of optical anisotropy (Δn), goodlow-temperature miscibility with other liquid crystals, a low rotaryviscosity (γ1), a relatively high clearing point (CP) and good UVstability and high-temperature thermal stability.

Compounds of Formulas (III1-III12) with negative dielectric anisotropy(Δ∈) can be used for distributing compounds with positive and negativedielectric anisotropy (Δ∈), in particular for distributing compoundswith negative dielectric anisotropy (Δ∈), and have different values ofR,

Z, X, m and n, and when all variables have big or small polarizationtowards the molecule short axis direction, the value of dielectricanisotropy (Δ∈) can be between −10-0; due to the different conjugationextent of liquid crystal molecules of different structures, the opticalanisotropy (Δn) can be between 0.05-0.40; and when m+n=2, the clearingpoint can be between 0-100° C., however, when m+n>2, the clearing pointcan be over 100° C. or even reach 200° C. In addition to suchcharacteristics, compounds of Formulas (III1-III12) also have goodlow-temperature miscibility with other liquid crystals and are thereforeable to improve the low temperature characteristics of the mixed liquidcrystal.

Compounds of Formula I can preferably be compounds of Formulas(IV1-IV6), (V 1-V 11) and (VI1-VI7):

wherein, R independently represents a hydrogen atom (H) or a C1-C5alkyl;X independently represents F, CI, OCF₃, CF₃, CN, H, a C1-C5 alkyl, aC1-C5 alkoxy, a C2-C5 alkenoxy, a C2-C5 alkenyl or a C2-C5fluoro-substituted alkenyloxy;(F) independently represents F or H.

The present invention provides a liquid crystal mixture containingcomponent A, which is composed of any or more of the compounds statedabove.

The said liquid crystal mixture can also contain components B and C, ofwhich, component B is composed of one or more of the compounds ofFormula VII, and component C is composed of one or more of the compoundsof Formula VIII:

In the Formula VII and Formula VIII, R₁ and R₂ each independentlyrepresent a C1-C6 alkyl or a C2-C6 alkenyl;

R₃ represents H, F, a C2-C6 alkenoxy or a C2-C6 fluoro-substitutedalkenyloxy;

represents one or more of -1,4-cyclohexylidene, -1,4-phenylene andfluoro-1,4-phenylene;p represents 2 or 3;(F) independently represents H or F.

The mass ratio of the said component A, B and C is preferably1-40:5-50:5-80, and is more preferably 10-35:15-45:25-75.

The said one or more of the compounds of Formula VII are preferably oneor more of the compounds of the following structural formulas:

The mass fraction of the compound of Formula VII in the liquid crystalcomposition is preferably 5-55, and more preferably 20-45, and due toits low rotary viscosity (γ1), such compound can reduce the rotaryviscosity (γ1) of the liquid crystal composition if it is used forliquid crystal composition, and the rotary viscosity (γ1) of the liquidcrystal composition will drop as the volume of addition of compound ofFormula VII increases, besides, other parameters will also be affectedby that.

The said one or more of the compounds of Formula VIII are preferably oneor more of the compounds of the following Formulas (VIII1-VIII12):

In the Formula VIII1-VII12, R₁ and R₂ each independently represent aC1-C6 alkyl or C2-C6 alkenyl.

The liquid crystal compositions of the present invention are prepared byseveral compounds, and are generally produced from the mixing of liquidcrystal monomers of 5-20 types. Owing to their different performanceparameters, each monomer will play a different role in the mixturesystem, and the formula engineer can, through preferring differentmonomer and optimizing the proportion of different monomers, adjust allperformance parameters of the mixed liquid crystal such as dielectricanisotropy (Δ∈), optical anisotropy (Δn), nematic phase of widetemperature range (crystallization point and clearing point (CP)), lowrotary viscosity (γ₁), elastic constant (K), cryogenic property,transmittance and other parameters, to adapt to the requirements of thedisplay devices and the collocability with PI and sealent used by thedisplay devices, so as to avoid some poor display.

The liquid crystal mixtures as involved in the present invention havewide scope of dielectric anisotropy (Δ∈) (the value of which can be setbetween 0.060-0.350), good low temperature miscibility with other liquidcrystals, a low rotary viscosity (γ₁) (lower than 150 mPa·s, or even at60mPa·s), high clearing point (CP) (any value from 60° C. to 120° C. isattainable), and good UV stability and high temperature stability, andtherefore can be used for different display modes and are able tosatisfy the requirements for liquid crystal performance under differentdisplay modes in terms of thickness of liquid crystal cell, responsetime, driving voltage and low viscosity.

The present invention is directed not only to the liquid crystalcompositions of the liquid crystal compounds of Formula I, but also tothe liquid crystal display devices containing such liquid crystalcompositions. The said display devices refer to VA display, IPS display,FFS display, TN display and STN display.

The VA display can be MVA, PVA, PSVA, UV²A; and IPS display includespositive and negative IPS display; FFS display includes positive andnegative FFS display.

The liquid crystal compositions of the present invention may be addedwith levorotatory or dextrorotary chiral dopants to form a chiralnematic phase.

After exposure to high temperature, UV or visual light, the liquidcrystal or the trace impurities therein can easily enter into theexcited state or create free radicals, and since the chemical characterof the excited state or free radicals is very active, it will be likelyto lead to oxidation or other chemical reaction that will cause thedecline in quality of the liquid crystal. Furthermore, the liquidcrystal compounds of the present invention may be added in dopants ofvarious properties during synthesis and use, and the content of dopantsis preferably 0.01-1%, and such dopants are mainly antioxidants,ultraviolet absorbents and light stabilizers, which are used to improvethe stability of liquid crystal, enhance quality and extend the servicelife of the mixed liquid crystal.

The antioxidants, ultraviolet absorbents and light stabilizers arepreferably: UV-P,

wherein, s is an integer selected from 1-10.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is the mass spectrum of compound (1-b).

FIG. 2 is the mass spectrum of compound (2-c).

FIG. 3 is the DSC curve of compound (1-b).

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are described below. It is,however, expressly noted that the present invention is not limited tothese embodiments. Unless otherwise stated, the methods are conventionalmethods, and the raw materials can be obtained from public domains andby commercial methods.

As used in the embodiments and examples, the specific meaning and testconditions of the symbols are as follows:

Cp: unit ° C., means the clearing point of liquid crystal.

S-N: unit ° C., means the melting point at which the liquid crystalchanges from crystalline solid into nematic phase.

Δn: optical anisotropy, Δn=n_(o)−n_(e), wherein n_(o) is the refractiveindex of ordinary light, and n_(e) is the refractive index ofextraordinary light, and the test conditions are 589 nm, 25±0.5° C.

ΔE: dielectric anisotropy, Δ∈=∈∥−∈⊥, wherein, ∈∥ is the dielectricconstant parallel with the molecular axis, and ∈⊥ is the dielectricconstant perpendicular to the molecular axis, and the test conditionsare 25±0.5° C.; 1 KHz; HP4284A; and 5.2 micron TN L-box.

γ1: rotary viscosity, unit: mPa·s, and the test condition is 25±0.5° C.

VHR: voltage holding ratio (%), the test conditions are 20±2° C.,±5Vvoltage, 10 ms pulse width and 16.7 ms voltage holding time. The testequipment is the TOYO Model 6254 liquid crystal performancecomprehensive tester.

The reaction process is usually monitored by the TLC, and the generalpost-processing at the end of reaction includes washing, extract, dryingafter combination of organic phase, solvent distillation under reducedpressure, and recrystallization and column chromatography. And it willbe easy and obvious to those skilled in the art to carry out the presentinvention in accordance with the following description.

Route 1:

represents phenylene or fluoro-substituted phenylene, and n=1;

M represents Br2, I2;a: Mg Et₂Ob: PdCl2 dppp Et₂O

Route 2:

represents phenylene or fluoro-substituted phenylene, and n=2;

c: PPh3 DMF 100° C.d: THF, potassium tert-butoxide, −5° C.e: H2, ethanol Pd/C

Route 3:

f: NaOH, Water, CHBr3, TBAB, EtOH refluxg: Pd/C EtOH

Example 1

0.72 g (0.03 mol) metal Mg spalls were placed in the 100 ml three-neckedflask with nitrogen charging in to replace air. 20 ml diethyl ether wasadded to cover the Mg spalls. The mixture was heated to reflux. 20 mldiethyl ether solution with 4.05 (0.03 mol) cyclopropylmethyl bromideswas instilled, and the reaction was soon initiated. Keep the mixturemicro-boiling until the instilment was finished. And the mixture shouldreflux for another 30 minutes after instilment.

7.62 g (0.02 mol) 4″-Bromo-2′,3,4,5-PTFE-1,1′;4′,1″-terphenyl wereplaced in another 250 ml three-necked flask with nitrogen charging in toreplace air. 30 ml diethyl ether was added to dissolve. 0.2 g PdCl2 dpppwas added as catalyst, and controlled the temperature at 15±5° C. Thesaid Grignard reagent was instilled, and refluxed for another 5 hoursafter instilment.

After regular post-processing, 3.27 g products (1-a) were gained, withGc:99.92%.

With reference to the synthesis method set forth in Example 1, onlyreplace part of the raw materials, the following compounds can besynthesized.

Mp: 28.5° C., please see FIG. 1 for (1-b) MS spectrum and FIG. 3 for DSCcurve.

Δ∈[1 KHz, 20° C.]: 27.8

Δn[589 nm, 20° C.]: 0.198

Cp: 106° C.

Example 2

Step 1:

20 g (0.148 mol) cyclopropylmethyl bromide, 39.3 g (0.15 mol)triphenylphosphine and 30 ml DMF were placed in a 250 ml three-neckedflask, and maintained the temperature at 100-110° C. for 6 hours, andthen cooled to 50° C., and poured 200 ml ethyl acetate into the flaskand stirred till the occurrence of a lot of white solid. Afterfiltering, 34 g products of cyclopropyl methyl bromidetriphenylphosphine salt (2-a) were obtained.

Step 2:

34 g (0.084 mol) cyclopropyl methyl bromide triphenylphosphine salt and400 ml THF were placed into a 1 L three-necked flask, and chargednitrogen into the flask for protection, and then cooled to −10° C.Maintained the temperature and added in 11 g potassium tert-butoxide bystage, heated up to 0° C. to react for half an hour.

The resolution of 23.1 g (0.07 mol)4″-Bromo-2′,3,4,5-PTFE-1,1′;4′,1″-terphenyl and 100 ml THF wasinstilled, and the temperature was controlled at 0-5° C. After 20minutes, the instilment finished and the mixture was then allowed fornatural temperature rise to room temperature to react for 1 hour.

After regular post-processing, 21.2 g products of (2-b) were obtained,with a reaction yield of 82% and Gc:99.6%.

Step 3:

21.2 g (2-b), 1 g Pd/C, 200 ml ethanol and 50 ml methylbenzene wereplaced into a 500 ml three-necked flask, and conducted 4 hydrogensubstitutions, and charged hydrogen at room temperature, reacted for 15hours.

After products' Gc analysis, 3% products from ring-opening reaction ofcyclopropyl were found, and after filtering catalyst and 4-5recrystallization, and 15.6 g (2-c) were obtained with a reaction yieldof 73.5% and Gc:99.85%.

Please see FIG. 2 for MS spectrum.

With reference to the synthesis method set forth in Example 2, onlyreplace part of the raw materials, the following compounds can besynthesized:

Example 3

Step 1:

4.0 g (0.1 mol) NaOH, 4.0 g water, 0.01 g tetrabutylammonium bromide and0.5 ml ethanol were placed into a 100 ml three-necked flask and stirredto dissolve. Added in 6.08 g (0.02 mol) (1-a) and 25 g bromoform andagitated and heated to reflux for complete reaction. After regularpost-processing, 5.99 g (1-b) were obtained, with a reaction yield of63%.

Step 2:

Dissolved 5.99 g (0.0126 mol) (1-b) in 100 ml ethanol and then added in0.6 g Pd/C and 0.013 mol sodium acetate, and stirred at roomtemperature. Let the mixture react for 14 hours. After regularpost-processing, 3.0 g (1-c) were obtained with a reaction yield of 75%.

Example 4

Used

to replace (1-a) in Example 1, and the synthesis process and method issame as that of Example 1, and with slight change known to those skilledin the art, the target compound (2-a) can be synthesized.

With reference to the synthesis method set forth in Example 3, onlyreplace part of the raw materials, the following compounds can besynthesized:

Example 5

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

28

10

8

8

8

8

10

20 Δε[1 KHz, 20° C.]: 9.10 Δn[589 nm, 20° C.]: 0.122 Cp: 76° C. γ₁[25°C.]: 68 mPa · s

This liquid crystal composition has an appropriate Δ∈, a large Δn, a lowγ₁ and an appropriate Cp, and fits for liquid crystal materials for TN,IPS, FFS-TFT display with rapid response and low cell gap.

The mixture was kept at −30° C. for 400 hours, and the compounds ofFormula I crystallized.

Example 6

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

30

10

8

8

8

10

12

14 Δε[1 KHz, 20° C.]: 7.8 Δn[589 nm, 20° C.]: 0.113 Cp: 92° C. γ₁[25°C.]: 85 mPa · s

This liquid crystal composition has an appropriate Δ∈, an appropriateΔn, a low γ₁ and a high Cp, and fits for liquid crystal materials forTN, IPS, FFS-TFT display with rapid response.

The mixture was kept at −30° C. for 400 hours, and the compounds ofFormula I crystallized.

Example 7

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

16

16

4

8

16

20

20 Δε[1 KHz, 20° C.]: 5.7 Δn[589 nm, 20° C.]: 0.0946 Cp: 63.9° C. γ₁[25°C.]: 142 mPa· s

Example 8

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 1

 8

15

15

 4

10

 2

23

22 Δε[1 KHz, 20° C.]: 2.6 Δn[589 nm, 20° C.]: 0.141 Cp: 90° C. γ₁[25°C.]: 74 mPa · s

Example 9

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

10

20

10

5

20

10

 5

20 Δε[1 KHz, 20° C.]: 12.5 Δn[589 nm, 20° C.]: 0.138 Cp: 128° C. γ₁[25°C.]: 174 mPa · s

Example 10

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 2

10

10

10

20

 5

12

 8

 8

 7

 8 Δε[1 KHz, 20° C.]: 5.2 Δn[589 nm, 20° C.]: 0.108 Cp: 143° C. γ₁[25°C.]: 143 mPa · s

Example 11

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 3

 5

13

11

10

 5

 7

21

20

 5 Δε[1 KHz, 20° C.]: 6.6 Δn[589 nm, 20° C.]: 0.102 Cp: 87° C. γ₁[25°C.]: 91 mPa · s

Example 12

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 1

 2

 2

 2

12

12

35

17

 8

 9 Δε[1 KHz, 20° C.]: 10.5 Δn[589 nm, 20° C.]: 0.150 Cp: 148° C. γ₁[25°C.]: 267 mPa · s

Example 13

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 8

15

19

19

20

19 Δε[1 KHz, 20° C.]: 9.6 Δn[589 nm, 20° C.]: 0.112 Cp: 80° C. γ₁[25°C.]: 92 mPa · s

Example 14

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

 1

 5

15

11

 5

18

20

25 Δε[1 KHz, 20° C.]: 7.3 Δn[589 nm, 20° C.]: 0.137 Cp: 94° C. γ₁[25°C.]: 91 mPa · s

Example 15

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

4

8

8

8

6

6

2

2

16 

8

28 

4 Δε[1 KHz, 20° C.]: 4.8 Δn[589 nm, 20° C.]: 0.140 Cp: 102° C. γ₁[25°C.]: 62 mPa · s

Example 16

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

10

 5

20

20

11

 5

 9

 5

15 Δε[1 KHz, 20° C.]: 4.4 Δn[589 nm, 20° C.]: 0.083 Cp: 81° C. γ₁[25°C.]: 62 mPa · s

Example 17

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

15

 5

 1

11

15

18

10

15 Δε[1 KHz, 20° C.]: 4.5 Δn[589 nm, 20° C.]: 0.095 Cp: 110° C. γ₁[25°C.]: 156 mPa · s

Example 18

A liquid crystal composition.

Liquid crystal compound Mass percentage (%)

10

 2

13

10

15

20

 3

13

14 Δε[1 KHz, 20° C.]: 3.5 Δn[589 nm, 20° C.]: 0.154 Cp: 132° C. γ₁[25°C.]: 211 mPa · s

Example 19

Liquid crystal mixture M containing (1-b).

Liquid crystal compound Mass percentage (%)

10

30

15

15

 5

25 Δn[589 nm, 25° C.]: 0.0659 Δε[1 KHz, 25° C.]: 6.8 Cp: 50° C. γ₁[25°C.]: 60.8 mPa · s

The mixture was kept at −30° C. for 400 hours, with no crystallization.Replaced (1-b) in the composition with

or

of equivalent weight ratio to form a new composition, and used the newcomposition to run a low temperature test. The new composition was keptat −30° C. for 400 hours, with crystallization. The crystallized monomerwas

or

In the liquid crystal mixture M containing (1-b), other monomers otherthan (1-b) are common liquid crystal monomers for the time being, withstable chemical properties and good UV stability and high-temperaturethermal stability.

After heating at 100° C. for 12 hours and UV 5000 mJ processing, the VHRdata contrast of the liquid crystal mixture M before and afterprocessing is as follows:

VHR (%, 5.0 V, VHR (%, 5.0 V, 16.61 ms) 166.7 ms) Before Processing99.65 99.28 After High- 99.59 99.20 Temperature Processing After UVProcessing 99.61 99.24

After the UV and high temperature processing, the VHR data of the liquidcrystal only slightly declines and still maintains at an ideal level,which indicates a good stability.

The liquid crystal compounds of Formula I have good cryogenic property,good UV stability and high temperature thermal stability, and will havedifferent Δn, Δ∈, Cp, γ1 properties when the values of R,

Z, X, m and n differ, and therefore have a wide range of application andcan be used for preparing liquid crystal mixtures with differentparameters.

What is claimed is:
 1. A liquid crystal compound of Formula I:

wherein, R is H or a C1-C5 alkyl; m, e, n each is 0, 1 or 2; Z is asingle bond, —CF₂O—, —CH₂CH₂—, —CH₂O—, —C≡C—, —OCH₂—, or —OCF₂—; X is F,CI, OCF₃, CF₃, CN, H, a C1-C5 alkyl, a C1-C5 alkoxy, a C2-C5 alkenoxy, aC2-C5 alkenyl, or a C2-C5 fluoro-substituted alkenyloxy;

each is phenylene, or fluoro-substituted phenylene.
 2. A compoundselected from a group consisting of:

wherein R is H or a C1-C5 alkyl; n is 1 or 2; X is F, CI, OCF₃, CF₃, CN,H, a C1-C5 alkyl, a C1-C5 alkoxy, a C2-C5 alkenoxy, a C2-C5 alkenyl, ora C2-C5 fluoro-substituted alkenyloxy; (F) is F or H; and X₁ is a C1-C5alkyl or a C1-C5 alkoxy.
 3. A liquid crystal composition comprisingcomponent A, wherein component A comprises a compound of claim
 1. 4. Theliquid crystal composition of claim 3, further comprising components Band C, wherein component B comprises at least one compound of FormulaVII, and component C comprises at least one compound of Formula VIII:

wherein R₁ and R₂ each is a C1-C6 alkyl, or a C2-C6 alkenyl; R₃ is H, F,a C2-C6 alkenoxy, or a C2-C6 fluoro-substituted alkenyloxy;

is one or more of 1,4-cyclohexylidene, 1,4-phenylene, orfluoro-1,4-phenylene; p is 2 or 3; and (F) is H or F.
 5. The liquidcrystal composition of claim 4, wherein a mass ratio of component A, Band C is 1-40:5-50:5-80.
 6. The liquid crystal composition of claim 5,wherein the mass ratio of component A, B and C is 10-35:15-45:25-75. 7.The liquid crystal composition of claim 4, wherein the compound ofFormula VII is selected from a compound of Formulas VII 1-VII 10:


8. The liquid crystal composition of claim 4, wherein the compound ofFormula VIII is selected from a compound of Formulas VIII 1-VIII 12:

and wherein in the Formula VIII 1-VIII 12, R₁ and R₂ each is a C1-C6alkyl or a C2-C6 alkenyl.
 9. An electro-optical display comprising theliquid crystal compound of claim
 1. 10. An electro-optical displaycomprising the liquid crystal composition of claim
 4. 11. Anelectro-optical display of claim 9, wherein the electro-optical displayis a VA display, IPS display, TN display, STN display or OCB display.